Some conventional vehicle lighting units can have a light source and a lens member disposed in front of the light source, like those disclosed in Japanese Patent No. 4047186 (or US 2004/0156209A1 corresponding thereto).
FIG. 1 is a vertical cross-sectional view illustrating a vehicle lighting unit 200 described in Japanese Patent No. 4047186.
As illustrated in FIG. 1, the vehicle lighting unit 200 includes a light source 210 having a semiconductor light emitting element, and a lens member 220 disposed in front of the light source 210. The lens member 220 can have a light incident surface 221, a first reflecting surface 222, a second reflecting surface 223, and a convex lens surface 224. The light incident surface 221 can have a semicircular shape so as to cover the light source 210 from above with the light source 210 disposed such that the light emission surface thereof faces upward. The first reflecting surface 222 can be disposed at a position located in a direction in which the light emitted from the light source 210 and entering the lens member 220 through the light incident surface 221 travels. The second reflecting surface 223 can extend from the lower end edge of the first reflecting surface 222 forward.
The vehicle lighting unit 200 with the above configuration can have the following problems.
Since the first and second reflecting surfaces 222 and 223 can be formed by deposited metal applied on the surface of the lens member 220 to be a reflecting surface having a reflectance of about 95% at maximum, the reflection loss (light loss) due to the deposited metal reflecting surfaces 222 and 223 can occur, thereby reducing the light utilization efficiency. In addition, the facilities, additional process, metal material, etc. for metal deposition are required, resulting in cost increase. There also arises another problem in that the deposited metal reflecting surfaces 222 and 223 (reflecting films) have a reduced durability.